Note the IP address has gone on the second attempt! I didn't drop the connectionI tried with optus and gmail servers - same result

Finally power cycle - then a THIRD attempt - result identical to the FIRSTWhich makes me think the modem is receiving all the commands - and getting into 'a mode' where it won't accept another 'send' until the previous one is sent, or the modem is power cycled (clearing the operational states)

Experienced responders have a nose for laziness, (they were beginners once)... Sure, there are trolls, chest-beaters, and pretenders - but the help you'll get here is about as good as it gets - if you try to help youself!.

I have a 3G module in the post so I can't help yet but maybe once it arrives we can collaborate. I did however buy the sim5216 because there appears to be a lot more AT command manuals related to HTTP access. I'm not sure what the difference the two modules is though. The sim800-900 had very similar AT commands, so with any luck the 5216 and 5320 will be similar too. Have you tried using the SIM5216 at command manual?

I also can't remember exactly why, but there was a reason I couldn't use SIM900 modules with my gmail account. I think it was to do with port access on googles end not allowing the type of connection the GSM module makes. Not sure if the SIM5320 has a way around that

Thanks for the thoughts.I'lll take a look at the 5216 ref. manuals... as noted above, the 5320 implements BOTH the older SMTP commands, as well as the newer CSMTPSxx commands - which I decided to go with for future-proof compatibility - but if it gets too hard, I'll fall back to the older commands for now.

There are a number of error possibilities - and only these two show up... 8=NETWORK ERROR 255=UNKNOWN ERROR...Are the least helpful... !

There are specific error responses for server, recipient, authentication etc - but they all seem to be for 'later' (!)

Experienced responders have a nose for laziness, (they were beginners once)... Sure, there are trolls, chest-beaters, and pretenders - but the help you'll get here is about as good as it gets - if you try to help youself!.

Experienced responders have a nose for laziness, (they were beginners once)... Sure, there are trolls, chest-beaters, and pretenders - but the help you'll get here is about as good as it gets - if you try to help youself!.

I hadn't been playing with the GPRS (data) side of things - but this code certainly worked last time I touched it.I suspect it could be tweaked a bit for efficiency - but it was robust - which counts!

My current call in-out /SMS tools are asynchronous - and I really should upgrade this as well - so the main loop() never blocks while the modem is working in the background

Experienced responders have a nose for laziness, (they were beginners once)... Sure, there are trolls, chest-beaters, and pretenders - but the help you'll get here is about as good as it gets - if you try to help youself!.

Hello.I would like to continue and develop the topic of sending a letter to an email via 3G shield. Interested in this topic. I stumbled upon a project where the author transmits with the help of sim5320 to an email not just text, but first takes a photo with the camera VC0706, and then sends it with the attached photo. In short: this is an email camera. I think someone else might be interested too.Link: https://www.instructables.com/id/Email-Camera-VC0706-3G-Shield-Arduino-M0-Analogue/